One well-known type of insulating glazing unit comprises two sheets of glass that are separated by a gas layer, such as a layer of air, which are spaced apart and held together by means of a spacer frame consisting of folded hollow sections or of sections assembled by central and/or angle components called connectors. The 90° angle components are usually called brackets.
The sections are provided with a molecular sieve, the purpose of which is in particular to absorb the water molecules trapped in the air interlayer during manufacture of the glazing, which molecules would be liable to condense in cold weather, which would cause fogging to appear.
To ensure that the glazing is sealed, the spacer frame is bonded to the glass sheets by a bead of elastomer of the butyl rubber type applied directly to the sections forming the spacer frame by extruding it through a nozzle.
Once the glazing has been assembled, the elastomeric sealing bead has the function of providing temporary mechanical retention of the glass sheets. Finally, a crosslinkable sealing mastic, of the polysulfide or polyurethane type, is injected into the peripheral groove bounded by the two glass sheets and the spacer frame, thereby completing the mechanical assembly of the glass sheets. The purpose of the butyl rubber is mainly to seal the inside of the glazing from water vapor, whereas the mastic seals against liquid water or solvents.
The hollow sections used are generally made of metal, such as aluminum. However, for some time now plastic sections have been used, such as those described in patent application EP 0 852 280. They thus have a lower coefficient of thermal conductivity, providing better thermal insulation power for the glazing.
Moreover, the section ends are assembled, to form the frame, by metal connectors, or at least connectors based on a plastic and having fastening/retaining elements made of metal. The connector is forcibly fitted into the hollow ends of the sections and held in place thanks to lateral retaining projections.
In the case of an entirely metallic connector, the projections are for example oriented in the opposite direction to the direction in which tension would be applied in order to pull on the section ends in the case of dismantling. Such a connector is described for example in patent application EP 0 283 689. However, this type of connector has, in particular at the lateral projections, sharp corners which may run the risk of causing injuries when handling the connector.
When the connector is not exclusively made of metal, it has at least its projecting retention/fastening elements made of metal, for example in the form of a needle that projects on either side of the lateral faces of the connector. However, these metal retention elements bite into the plastic of the sections when the connector and the sections are brought into cooperation, thereby creating internal grooves that weaken the section ends.
Patent application FR 2 604 210 proposes a connector which, provided with lateral retention projections, is however made of a plastic, thereby advantageously eliminating all sharp corners and consequently eliminating any risk of an injury deriving therefrom. This connector is nevertheless easy to fit into the hollow section ends, without any risk of weakening said ends, owing to the different metallic material constituting the section ends. This is because, at the time when said document was disclosed, the existing sections were exclusively metallic.
Also, for section ends made of plastic, a solution has therefore been used for some time. This involves connectors made entirely of plastic that are oversized considerably along their entire length so as in this way to ensure retention after they have been forcibly inserted into the sections. However, this solution often causes the sections to burst, and has therefore been abandoned.